In general, a mechanical device such as an engine or a transmission of a machine (hereinafter, referred to as “vehicle”) such as an automobile or a construction machine requires that oil should be supplied to a sliding part in order to perform a smooth operation of an operating part and maintain the lifespan of the operating part for a long period of time.
Viscosity and lubrication properties of the oil supplied to the engine of a vehicle are deteriorated over time due to oxidation by the contact between the oil and the air, abrasion of the sliding part, or the mixture of the oil and impurities introduced into the engine from the outside. Thus, a driver or an operator must check the state of the oil periodically to exchange the oil at the appropriate times.
FIG. 1 is a view showing the installation state of a conventional level gauge in accordance with the prior art, and FIG. 2 is a view showing the configuration of a conventional level gauge in accordance with the prior art.
Referring to FIGS. 1 and 2, the conventional level gauge includes a pipe (hereinafter, referred to as “tube”) 30 made of a metal material that is mounted on a swing decelerator 10 of a vehicle and a gauge part 50 that is accommmodatably joined to the tube to measure the level of oil.
The gauge part 50 includes a hand grip 53, a sealing member 55, and an inspection part 57.
The hand grip 53 refers to a part that is gripped by an inspector's hand so that the inspector separates the gauge part 50 from the tube 30 to check the state of oil or couples the gauge part 50 to the tube 30. The sealing member 55 refers to an element that allows the gauge part 50 to be securely fixed to the tube 30 and simultaneously hermetically seals the tube 30. The inspection part 57 refers to an element that longitudinally extends inside an oil tank and allows for collection of an oil sample needed to check the state of the oil contained in the oil tank
In the above configuration, the inspector pulls up the hand grip 53 to separate the gauge part 50 from the tube 30, and then identifies the state of the oil sample collected at a lower end of the inspection part 57 so that the inspector can check the state of the oil contained in the oil tank.
The gauge part 50 has concavo-convexes 56 formed on the outer circumferential surface of the sealing member 55 and the sealing member 55 is insertingly fitted into an upper end of the tube 30 in a press-fit manner.
However, the conventional level gauge entails a problem in that since the sealing member 55 is press-fittingly coupled to the tube, air inside the decelerator 10 is not easily discharged to the outside. In addition, the air inside the decelerator is expanded over time by heat generated in the operation process of the engine to cause the internal pressure of the engine to be increased, resulting in damage of a packing member or deterioration of operating efficiency of the machine.
Conventionally, in an attempt to solve such a problem, a discharge groove (not shown) is formed on the outer circumferential surface of the sealing member 55 in juxtaposition with the inner circumferential surface of the tube 30 so as to discharge the air heated to the outside through the discharge groove. However, such a conventional level gauge still encounters a problem in that foreign substances or moisture is introduced into the oil tank from the outside, resulting in deterioration of the quality of the oil and reduction of the lifespan of the machine.